The pathogenesis, molecular biology, immunology, natural history, and therapy of human herpesvirus infections are being investigated. Immunocompetent and immunodeficient patients, including those with AIDS, who possess a wide range of herpesvirus infections have been identified and studied. During the past year we have extended our studies of chronic EBV infection, having identified a series of immunologic abnormalities in that syndrome; we have continued to study acyclovir suppression for frequently recurring or chronic herpes simplex infections, with encouraging results. Our major focus on the study of the molecular biology and latency of varicella zoster virus (VZV) DNA has continued. We have proven reactivation of latent VZV by restriction endonuclease analyses of isolates recovered from separate episodes of infection in the same individual. Recombinant clones were successfully used for rapid diagnosis of varicella and zoster infection. This year we have begun studies of the genetic expression of VZV, with at least preliminary characterization and mapping of a series of major and minor viral transcripts from the right hand end of the viral genome. During the coming year we plan to initiate marker rescue studies to map the genetic loci associated with VZV resistance to antiviral drugs.